Crystal structure of higenamine [1,2,3,4-tetrahydro-1-(4-hydroxybenzyl)isoquinoline-6,7-diol] hydrobromide
Higenamine, a heart-beat regulating compound, recently extracted from Aconitum japonicum Thunb. was examined by X-ray crystallographic analysis as its hydrobromide. Crystals are triclinic, space group P, with Z= 2 in a unit cell of dimensions a= 10.071 (7), b= 9.111 (7), c= 9.643(7)Å, α= 105.56(8), β= 103.73(7), γ= 64.73(5)°. The structure was refined by full-matrix least-squares methods to R 12.7% for 2 878 independent reflections visually estimated from photographic data. The conformation of the molecules and the system of binding of the bromine atom are almost identical to those of coclaurine in coclaurine hydrobromide monohydrate. The molecular packing and the hydrogen-bonding network in higenamine crystals were determined. The enhanced β-adrenergic stimulating activity of higenamine compared to coclaurine is discussed.